Snap switch with positive-drive breaking action

ABSTRACT

A snap switch capable of unfailingly the fixed open moving contacts disposed opposite fixed contacts. It includes, in a housing carrying the fixed contacts, a rocking central part carrying the moving contacts and means for restraining it on the housing, a slide which is provided with at least one cam for directly actuating the central part and which extends therethrough, said part being provided with an elastic thrust point and a snap-action contact breaking spring being positioned between the slide and the central part whereby to cause operation of the slide cam on the central part whereby to cause operation of the slide cam on the central part to simultaneously arm the spring and raise the central part against the countering action of the elastic thrust point followed by sudden release of the central part and tripping thereof responsively to the spring, backup driving means being additionally provided to operate in the event of failure of the spring.

United States Patent [72) Inventors Fernand Santerre Orgeval; FrancisLibaud, Nanterre, both of, France [21] Appl. No. 855,923 [22] FiledSept. 8, 1969 [45] Patented June 15, 1971 [73] Assignee La TelemeeaniqueElectrique Nanterre, France [32] Priority Sept. 9, 1968 [33] France [31]165522 [54] SNAP SWITCH WITH POSITIVE-DRIVE Primary Examiner-DavidSmith, Jr. Attorney-Karl W. Flocks ABSTRACT: A snap switch capable ofunfailingly breaking open moving contacts disposed opposite fixedcontacts.

lt includes, in a housing carrying the fixed contacts, a rocking centralpart carrying the moving contacts and means for restraining it on thehousing, a slide which is provided with at least one cam for directlyactuating the central part and which extends therethrough, said partbeing provided with an elastic thrust point and a snap-action contactbreaking spring being positioned between the slide and the central partwhereby to cause operation of the slide cam on the central part wherebyto cause operation of the slide cam on the central part tosimultaneously arm the spring and raise the central part against thecountering action of the elastic thrust point followed by sudden releaseof the central part and tripping thereof responsively to the spring,backup driving means being additionally provided to operate in the eventof failure of the spring.

PATENTEDJUNISIQYI 35 5,3253

sum 1 OF 5 PATENTEDJUNISISH 3.585.326

SHEEI 2 BF 5 i gkm m? a -05; a 8 ma. 8 on m E m A PATENTED JUN] 5 I97!SHEET 3 [1F 5 SNAP SWITCH WITI-I POSITIVE-DRIVE BREAKING ACTION Thisinvention relates to the snap switches used in industry to control theoperation of machines and other mechanical devices and provides meansfor ensuring unfailing breaking of the contacts even if the springs forproducing the snap effect or the elastic restoring action on the variousmoving parts were unable to function. Already known are many mechanically operated switches in which contacts are moved with a snap actioneven though the mechanical action itself may be very slow.

Also known is an electric switch which does not use the tumbler effectbut comprises a slide and a switching element moving therealong. Thisswitching element, which is restrained in either of the two switchingpositions by a locking member, changes its position responsively to aspring interposed between the slide and the switching element when theslide, which comprises a cam, unlatches the locking member and therebyreleases the switching element. Said spring is contained in a guidingenclosure formed by the slide and the switching element.

In one prior art switch, a contact-bearer is connected to a beam-levertype mechanical member which is alternately restrained in two stablepositions by hooked levers, with the actuating member first tensioning aspring and then releasing one of the levers. Should the spring break,however, the contact-bearer is no longer actuated. Furthermore, in caseswhere the switch is required to break fairly high current intensities,notably in direct current, the rupturing arc may in some cause thecontacts to fuse together.

The above-mentioned switches do not normally include failsafe drivemeans whereby the contacts are separated by a mechanical force in allcases. Moreover, prior art switches have often tended to be complicatedand to include a large number of parts, hooking levers and springs.

The present invention overcomes these drawbacks and provides notableimprovements. It relates to a basic switch of very simple design, inwhich the translating motion of an actuating slide causes movingcontacts to be shifted with a snap action or through a direct driveshould the snap action have been prevented. The invention furtherprovides for a rotary wiping effect between the fixed and movingcontacts.

The invention further relates to a lever-operated switch, usually knownas a limit switch, for use on machines for controlling the stroke ortravel of the moving parts, said leveroperated switch being obtained bymechanically adapting the basic switch of this invention. Lastly, theinvention relates to a method of elastically operating the switch leverthat includes the use of a damping device for preventing the lever fromhunting about its resting position.

Essentially, the snap switch of this invention is characterized in thatit includes a central part having two stable positions and bearingmoving contacts positioned opposite fixed contacts, means for securingthe same to a fixed part of the switch and an elastic bearing pointtherefor, a slide comprising at least one actuating cam and extendingthrough said central part, and a spring disposed within said centralpart and armed by said slide which, at the same time, lifts the centralpart until latching means are ultimately released and thereby allow thespring to relax and the central part to snap suddenly from one of itsstable positions to the other, backup means being provided in the eventof failure of the armed spring.

The description which follows with reference to the accompanyingnon/limitative exemplary drawings will give a clear understanding of howthe invention can be carried into practice. In the drawings:

FIGS. 1 through 4 are side elevation views of the different operatingconfigurations of one embodiment of a snap switch according to theinvention.

FIG. la is a fragmental section taken through the line a-a in FIG. I.

FIG. lb is an alternative embodiment of the trip system and the methodof fastening the spring of the central part in FIG. 1.

FIGS. 5 through 7 are partial longitudinal sectional views of stillanother embodiment of a snap switch according to the invention.

FIG. 8 is a cross-sectional showing of the embodiment of FIGS. 5 to 7.

FIG. 9 is a top view of the central part used in the embodiment ofFIGS.5 to 7.

FIG. 10 is a front view of a motion amplifier.

FIG. 11 is a top view in partial section of yet another embodiment of asnap switch according to this invention.

FIG. 12 is a fragmental longitudinal portrayal in section of theembodiment of FIG. 11.

FIG. 13 is a longitudinal sectional portrayal of a device for convertinga rotating motion into a translational motion, applicable forcontrolling the slides of snap switches according to this invention.

FIG. 14 is a front view ofa cam used in said motion converting device.

FIGS. 15 and 16 are front views of two dogs used in said motionconverting device; and

FIG. 17 shows the said two dogs in their engaged configuration.

In the embodiment shown in FIGS. 1 to 4, the said switch according tothe present invention includes a bridgeshaped central part I having fourlegs 2.

A slide 3 is movable along a slideway 4 formedin the switch housing 5and is formed with two flanges 6, and each flange can pass between twoof the legs 2 of central part 1.

The central part I is surmounted by a ring 7 through which extend twoblades 8 bearing moving contacts (not shown for greater clarity), aspring 9 being interposed between the blades in said ring.

Fixed contacts (likewise not shown) are positioned opposite the movingcontacts, which are four in number, each blade 8 carrying a movingcontact on either side of the ring.

Each leg 2 is formed with two sloping facets: an outer facet 10 and anend facet 12. The outer facet 10 cooperates with a fixed lateral stop13, and the end facet I2 cooperates turn with a fixed catch 14 and witha fixed ramp 15 extending up to the lateral stop 13.

The fixed stops 13, the fixed catches I4 and the fixed ramps I5 areformed on two members 16 rigid with the bottom of the main housing andpositioned on either side of slide 3. Each member 16 comprises two stops13, two catches l4 and two ramps 15.

The end facets 12 of legs 2 also cooperate with two earns 17 rigid withthe slide.

Opposite the members 16, central part 1 is offered a resilient bearingpoint consisting of a ball or roller 18 upon which thrust is exerted bya spring 19 or by a spring blade.

A further spring 20 is placed longitudinally beneath bridgeshapedcentral part 1 in such manner as to be restrained, in the restingposition shown in FIGS. 1 and 3, between the two flanges 6 of slide 3,and, in the operative position shown in FIGS. 2 and 4, between one ofthese flanges and a pair of legs 2 against which it abuts.

It will be clear from the foregoing that when the slide 3 is urged inthe direction of arrow f in FIGS. 1 and 2, the flange 6 located on theside where pressure is exerted will pass between the legs 2 on that sideand compress the spring 20 against the other two legs 2 of central partI.

At the same time, the earns 17 act upon those end facets of the feet 2which are opposite those traversed by the slide flange 6 and raisecentral part 1 until the facets 12 of said feet have ridden over thepeaks of cams I7 and until said feet disengage from catches l4.'At thlspoint the spring 20 relaxes and suddenly thrusts back the central partuntil it occupies the resting position shown in FIG. 3, which issymmetrical with that shown in FIG. I.

In the case of action exerted in the direction of arrow f in FIG. 3,central part 1 is caused to snap over into the symmetrical position ofFIG. 1 when, here again, the feet 2 opposite those traversed by theslide flange in question ride over the peaks of earns 17 and disengagefrom catches 14.

In the case of action exerted in the direction of either arrow f orarrow f,, the facets 12 on the feet opposite those traversed by theflange 6 in question slide along the ramps 15 as the central part 1snaps over, with the facets 10 of said feet abutting against the stops13 located before them.

Each time the central part 1 snaps over, the moving contacts are causedto snap open.

The preliminary lifting motion of central part 1 produces a wipingeffect between the fixed and moving contacts.

Should central part 1 be unable to snap over, a peg 21 (FIG. 4)positioned on the peak of each cam 17 acts upon those feet 2 which areopposite the ones traversed by one of the flanges 6 of slide 3, if forcecontinues to be exerted on the slide.

In the embodiment shown in FIGS. through the snap switch according tothis invention includes a central indented part 1a provided with twolateral rings 7a (FIGS. 7 and 8), each of which is traversed by twoblades 8a bearing moving contacts 22 on either side of the ring. Aspring 9a is interposed between the two blades.

Fixed contacts 23 equal in number to the moving contacts 22 are disposedon strips 24 rigid with the main housing.

Two pairs of catches 25 are formed respectively on two of the faces ofcentral part 1a and are adapted to engage in corresponding indents 26formed in fixed parts 27 on the main housing (see FIGS. 7 and 9).

The central part is traversed by a slide 311 formed with a cammingindent 170 which cooperates with an internal lobe 28 on central part 1a.

A spring 200 is lodged inside the central part in such manner as to berestrained, in the resting position, between two facing protrusions 29on slide 3a and, in operation, between one of these protrusions and anabutment wall 30 (FIG. 8) provided on either side of the slide, withinthe indentation of the central part.

A roller 18a supported on a spring lodged inside the central part isinterposed between the latter and the slide.

A push (f FIG. 5) ora pull (f FIG. 6) exerted on slide 3a causes centralpart I to be raised and simultaneously arms the spring 200 bycompressing it between one of the protrusions 29 on the slide and one ofthe abutment walls 30 on the central part.

The raising effect is obtained by the cooperation of hollow cammingsurface 170 with lobe 28 on the central part.

In the course of the raising process the catches 25 disengage from theirindents 26 and the armed spring a relaxes, causing the central part tosnap over from one tilted position to another tilted positionsymmetrical therewith (from FIG. 5 to FIG. 6, or vice versa).

Should snapover of the central part be unable to take place, a plate 31on the slide acts upon the central part so as to cause it to trip. Aforked amplifier device 32 (FIG. 10) may be interposed to that endoetween plate 31 and the central part. Obviously, two plates 31 and twoamplifier devices 32 are provided to operate respectively for operationin the direction f, and in the directionj}.

In the embodiment shown in FIGS. 11 and 12, control is positive only inthe direction f and is automatic in the opposite direction by virtue ofareturn spring 33. The latter is interposed between the main housing anda protrusion 34 on the slide 3b, which comprises only one actuatingplate 31b; only one amplifier device 32 is accordingly provided.

The slides may be actuated either off a part possessed of translationalreciprocating motion or off a part possessed of rotating motion about amidway position (as in the case of a machine-tool component, forinstance).

In the latter case, it is necessary to provide means for converting arotary motion into a linear motion.

FIG. 13 illustrates a device which permits such conversion andadditionally enables a controlled lever 35 to return into its midwayposition. Means are also provided to limit the angular travel of thecontrolled lever about its midway position.

Lever 35 is angularly rigid with an axle 36 forming an extension of ashaft 37 carrying a cam 38 formed with a lobe 38a and an indent 38b.

From either side of lobe 38a extend circle-arcuate ramps 39 whichterminate on a diameter of the cam at right angles to the diameterjoining the lobe to the indent. From either side of indent 38b extendcircle-arcuate ramps 40 terminating on the same diameter. The radius oframps 39 is smaller than that of ramps 40.

Lobe 38a, indent 38b and ramps 39 and 40 cooperate with cam followers 41carried on a slide 42 which is movable within a slideway 43 and guidedby a stud 44.

Slide 42 bears an arm 45 capable of being adapted upon the slide 3 ofasnap switch according to the invention, the housing of which isdesignated by reference numeral 5.

Motion of the cam- 38 accordingly causes translational motion of slide42 and hence of the switch slide 3.

Arm 45 may be caused to operate either on a slide designed for twopositive displacements (3 and 3a) or on one designed for only onepositive displacement (3b).

Carried on shaft 37 are two dogs 46 and 47. Dog 46 (FIG. 15) is free torotate over ninety degrees in the direction/' and carries a tang 48capable of rotating through degrees between two fixed stops 49 and 50.Two lands 64 and 65 are formed inside this dog, on either side of shaft37. The sides 70, 71 of these lands act as abutments for the two endsrespectively ofa pin 66 extending through shaft 37.

The dog 47 (FIG. 16) is free to rotate over 90 degrees in the directionf and carries a tang 51 capable of rotating through 90 degrees betweentwo fixed stops 52 and 53. Two lands 67 and 68 are likewise formedwithin dog 47, on either side of shaft 37, but are angularly offset by90 degrees in relation to lands 64 and 65. A pin 69 extends throughshaft 37 so that its two ends may bear against the sides 72, 73 of lands67 and 68.

When lever 35 is actuated in the directionf shaft 37 moves pin 66 intoabutment against the sides 70 and 71 of lands 64 and 65, respectively,of dog 46, thereby rotating the latter whereas dog 47 does not rotatebut shifts along shaft 37 and compresses a spring 57 interposed betweendog 47 and a fixed wall 58. The rotation of dog 46 is limited by thestops 49 and 50.

When lever 35 is actuated in the direction f pin 69 is in abutmentagainst the sides 72 and 73 of lands 67 and 68 respectively of dog 47,thereby rotating the latter whereas dog 46 does not rotate.

As it rotates, dog 47 is displaced longitudinally in the direction};along shaft 37 and compresses spring 57.

When spring 57 relaxes, lever 36 is restored to its midway or restingposition.

Spring 57 is engaged over a cylinder 60 which is rigid with dog 47 andembodies two blind holes 61 and 62. Blind hole 61 is adapted to receivethe end of shaft 37. In conjunction with a cylindrical head 63 rigidwith fixed wall 58, blind hole 62 forms a dashpot which prevents lever35 from oscillating about its resting position.

We claim:

1. A snap switch which operates from one stable position to anotherstable position and is capable of unfailing opening of contacts,comprising:

a housing having fixed contacts attached to said housing;

a rocking central part having moving contacts attached thereto andmounted in said housing to move from one stable position to another;

latching means on said central part and means engageable with saidlatching means for holding said central part against movement;

a slide provided with at least one cam means engageable with saidcentral part for releasing said latching means from said meansengageable with said latching means and said slide mounted forreciprocating motion in said houssaid central part having an openingtherethrough and said slide positioned for at least a portion of saidslide to pass through said opening;

a resilient thrust point means in operative contact with said centralpart to restrain the movement of said central part from one of itsstable positions to another;

a spring mounted for compression between a surface on said slide and anopposing surface on said central part at least during reciprocalmovement of said slide; and

supplemental switch drive means on said slide for engaging said centralpart during a portion of the reciprocating motion of said slide whensaid rocking central part has failed to move to its other stableposition during the reciprocating motion of said slide, to move saidcentral part off of a stable position.

2. A switch in accordance with claim 1 further characterized by saidmeans engageable with said latching means mounted rigidly to saidhousing.

3. A switch in accordance with claim 1 further characterized by saidcentral part having the shape of a bridge with two pairs of legs; and

said slide having a flange on each side, each of said flanges located topass between one of said pairs of legs on said central part and compresssaid spring between said flange and the other of said pair oflegs.

4. A switch in accordance with claim 3 further characterized by saidlatching means formed by the end portions of said legs;

said means engageable with said latching means mounted rigidly to saidhousing;

and said resilient thrust point formed on said housing.

5. A switch in accordance with claim 3 further characterized by saidsupplemental switch drive means being protrusions on said cam meanswhereby operation of the switch will take place despite any failureofsaid spring.

6. A switch in accordance with claim 1 further characterized by theopening in said central part being an indentation which accommodatessaid slide therein;

said slide having an indentation which accommodates said spring; and

said resilient thrust point being located between said slide and saidcentral part.

7. A switch in accordance with claim 6 further characterized by saidsupplemental switch drive including:

plates forming part of said slide on the end portions of said slide; and

an intermediate member between each of said plates and said centralpart.

8. A switch in accordance with claim 6 further characterized by saidslide operating the switch during each direction of reciprocation ofsaid slide; and

said central part having the components of the switch symmetricallydistributed on either side of said central part.

9. A switch in accordance with claim 6 further characterized by saidslide operating the switch during only one direction of reciprocation ofsaid slide;

said supplemental switch drive including:

a plate forming part of said slide on one end portion of said slide, and

an intermediate member between said plate and said central part;

and a return spring compressible between said housing and said slide onthe opposite end of said slide from said plate.

10. A switch in accordance with claim 1 further characterized by meansfor converting rotary motion into translational motion including:

an arm connected to said slide;

a shaft;

a pivotal control member in angularly rigid connection with said shaft;

a cam in angularly rigid connection with said shaft and positioned forcoacting with said arm.

1. A snap switch which operates from one stable position to anotherstable position and is capable of unfailing opening of contacts,comprising: a housing having fixed contacts attached to said housing; arocking central part having moving contacts attached thereto and mountedin said housing to move from one stable position to another; latchingmeans on said central part and means engageable with said latching meansfor holding said central part against movement; a slide provided with atleast one cam means engageable with said central part for releasing saidlatching means from said means engageable with said latching means andsaid slide mounted for reciprocating motion in said housing; saidcentral part having an opening therethrough and said slide positionedfor at least a portion of said slide to pass through said opening; aresilient thrust point means in operative contact with said central partto restrain the movement of said central part from one of its stablepositions to another; a spring mounted for compression between a surfaceon said slide and an opposing surface on said central part at leastduring reciprocal movement of said slide; and supplemental switch drivemeans on said slide for engaging said central part during a portion ofthe reciprocating motion of said slide when said rocking central parthas failed to move to its other stable position during the reciprocatingmotion of said slide, to move said central part off of a stableposition.
 2. A switch in accordance with claim 1 further characterizedby said means engageable with said latching means mounted rigidly tosaid housing.
 3. A switch in accordance with claim 1 furthercharacterized by said central part having the shape of a bridge with twopairs of legs; and said slide having a flange on each side, each of saidflanges located to pass between one of said pairs of legs on saidcentral part and compress said spring between said flange and the otherof said pair of legs.
 4. A switch in accordance with claim 3 furthercharacterized by said latching means formed by the end portions of saidlegs; said means engageable with said latching means mounted rigidly tosaid housing; and said resilient thrust point formed on said housing. 5.A switch in accordance with claim 3 further characterized by saidsupplemental switch drive means being protrusions on said cam meanswhereby operation of the switch will take place despite any failure ofsaid spring.
 6. A switch in accordance with claim 1 furthercharacterized by the opening in said central part being an indentationwhich accommodates said slide therein; said slide having an indentationwhich accommodates said spring; and said resilient thrust point beinglocated between said slide and said central part.
 7. A switch inaccordance with claim 6 further characterized by said supplementalswitch drive including: plates forming part of said slide on the endportions of said slide; and an intermediate member between each of saidplates and said central part.
 8. A switch in accordance with claim 6further characterized by said slide operating the switch during eachdirection of reciprocation of said slide; and said central part havingthe components of the switch symmetrically distributed on either side ofsaid central part.
 9. A switch in accordance with claim 6 furthercharacterized by said slide operating the switch during only onedirection of reciprocation of said slide; said supplemental switch driveincluding: a plate forming part of said slide on one end portion of saidslide, and an intermediate member between said plate and said centralpart; and a return spring compressible between said housing and saidslide on the opposite end of said slide from said plate.
 10. A switch inaccordance with claim 1 further characterized by means for convertingrotary motion into translational motion including: an arm connected tosaid slide; a shaft; a pivotal control member in angularly rigidconnection with said shaft; a cam in angularly rigid connection withsaid shaft and positioned for coacting with said arm.